Re: adding a trend line to ggplot2

[gsaray101]

On Monday, June 25, 2012 11:09:11 AM UTC-4, gsaray101 wrote:

I am working with a data frame like this:

 

 

df is this

Date       Variable  Value

1/1/2001   a            10

1/1/2001   b             100

1/1/2001   c              50

1/2/2001   a              15

1/2/2001  b                90

1/2/2001  c                60

etc

 

 

I like to draw a stack bar chart which I can with this:

 

ggplot(df, aes(x = Date, y = Value, fill= Variable)) + geom_bar(stat = "identity", position = "stack")+theme_bw()

 

I like to be able to add a trend to this stacked bar chart based on the total values by date. For example, total data fram would look like this:

 

total

Date   Value

1/1/2001  160

1/2/2001   175

etc

 

How can I a trend line using ggplot? Thanks for your help.

 

I could not find a good example on stakcoverflow. I can create the stack bar chart but I would like to add a an arrow line that will show the trend. Any ideas, anybody?

 

 

 

[adam.l...@pnc.com]

Hi, try this.

library(grid)
library(ggplot2)

df <- structure(list(Date = structure(c(1L, 1L, 1L, 2L, 2L, 2L), .Label = c("1/1/2001",
"1/2/2001"), class = "factor"), Variable = structure(c(1L, 2L,
3L, 1L, 2L, 3L), .Label = c("a", "b", "c"), class = "factor"),
    Value = c(10L, 100L, 50L, 15L, 90L, 60L)), .Names = c("Date",
"Variable", "Value"), class = "data.frame", row.names = c(NA,
-6L))

tot <- structure(list(Date = structure(1:2, .Label = c("1/1/2001", "1/2/2001"
), class = "factor"), Value = c(160L, 165L)), .Names = c("Date",
"Value"), class = "data.frame", row.names = c(NA, -2L))

ggplot(df, aes(x = Date, y = Value)) +

geom_bar(aes(fill=Variable),stat = "identity", position = "stack") +

theme_bw()+

geom_line(data=tot,aes(Date,Value,group=1),arrow=arrow())


Adam

From:	gsaray101 <gsara...@gmail.com>
To:	ggp...@googlegroups.com
Date:	06/26/2012 04:49 PM
Subject:	Re: adding a trend line to ggplot2
Sent by:	ggp...@googlegroups.com

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[gsaray101]

this is not what I am looking for. This draws curvy line on top of the stack bar. I am looking for a trend line (straigt, up or vertical or down: depending on the trend).

[gsaray101]

Adam:

 

I figured it out. I wanted to put the variables in stack and put a trend line on the total value to show where the trend is going. I can do this by this: geom_smooth(data=total,aes(Date,value,group=1), method="lm", size=2, color="darkblue")

 

I have another question. on the same graph. I would like to show the projected line for 6 months. Have you done anything like that?